pub fn odd_fibnacci_sum(threshold: u32) -> u32 {
    let (mut a, mut b) = (0, 1);
    let mut res = 0;
    while b <= threshold {
        if b % 2 == 1 {
            res += b;
        }
        (a, b) = (b, a + b);
    }
    res
}
